Fourteen newly discovered photographs of people incarcerated at the notorious S-21 prison are displayed at the offices of the Documentation Centre of Cambodia yesterday. Photograph: Hong Menea/Phnom Penh Post

To Sochanthy made an unusual discovery when his family packed up their home on Monivong Boulevard to relocate four months ago.

The 47-year-old government official was overwhelmed with a rush of memories as he stumbled upon 14 photographs of S-21 prisoners he had found as a teenager and kept stored in his post-1979 family home.

“I lived [after 1979] near the health university, and in 1983, I saw those photos and some other documents scattered under a tree on the corner of the street,” Sochanthy said, describing a Khmer Rouge bulletin, handwritten books and some photographs of Lon Nol soldiers marching.

“I chose only the photos to keep, because they looked like prisoner photographs I had seen at Tuol Sleng museum when my family visited after the Pol Pot regime,” he said, recalling a deserted building with clothes and torture implements strewn across the grounds.

“I thought that I could keep these for the future to show others who might recognise their family members.”

At the time a teenager, Sochanthy did not realise the significance of his find and later, when it was announced there would be a tribunal to trial Khmer Rouge crimes, he searched again for the photos he had chanced upon, but could not locate them – until now.

“I read a story last week on the internet about the person giving photos to [Documentation Centre of Cambodia director] Youk Chhang, so I decided to give the photos to him,” Sochanty said.

Youk told the Post by email that before the arrival of UNTAC in the 1990s “many documents about the Khmer Rouge were destroyed for the sake of peace and national reconciliation”.

“But I believed in the heart of the genocide survivors that some documents may have been saved by them who do not want the world and the future generations of Cambodia to forget the history of the Khmer Rouge,” Youk said.

“So, I have been chasing these rescued documents for years now. And it turned out that some have in fact been saved by the survivors.”